Networks connect many different kinds of electronic devices. Communication protocols and standards have been developed to standardize the exchange of data between electronic devices in a network. Among the most common types of network protocols are Ethernet, Token Ring, Fiber Optic Inter-Repeater Link (FOIRL), Copper Distributed Data Interface (CDDI), and Fiber Distributed Data Interface (FDDI). Ethernet, Token Ring and FDDI communications protocols commonly are used to move packets over local area networks (LANs). Higher layer protocols, such as TCP/IP, SPX/IPX and NetBIOS/NetBEUI, typically are used to control and route data transmissions. Other exemplary communications protocols include ATM and SS7. In general, a communications protocol is any format, definition, or specification that specifies the content or nature of data transmitted in a network or the link over which the data is transmitted. A protocol typically includes transmission rate specifications, wired or wireless link specifications, frame formats, blocking formats, text formats, stop/start indicators, framing and heading indicators, field definitions, checksum values, and carriage return and line feed (CRJLF) indicators.
Data may be transferred through a network using a variety of transmission cable technologies, including multimode optical fiber cables, single mode optical fiber cables, and copper cables (e.g., twinax and coax copper cables). Standard communications modules have been developed to transition between respective transmission cable media and the electronic components inside a host system (e.g., a computer or peripheral device). For example, an optoelectronics transceiver module enables bidirectional data transmission between an electrical interface and an optical data link. A copper transceiver module, on the other hand, enables bidirectional data transmission between two electrical devices. A communications module produces a standardized output to the host system in accordance with a compatible communications protocol, regardless of the medium (e.g., optical fiber or copper) through which the data is transmitted or received. A communications module may be integrally incorporated within a host system or a host system component (e.g., a network interface card (NIC)) or it may consist of a separate component that readily may be plugged into and unplugged from a host system. Among the common communication modules are transmitter modules, receiver modules, and transceiver modules.